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Gate Arrays

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FPGA

FPGA = Field Programmable Gate Array. That means you get to program it (in the field instead of in the factory).

It is possible to purchase a gate array containing a large number of NAND or NOR gates. These arrays can be programmed to simulate quite complex logic circuits. There is computer aided design software to make this task fairly easy. The advantages of using these chips are as follows...

Many chips can be replaced by one chip.
The one chip costs less than the many.
The one chip consumes less power than the many.
The one chip is smaller than the many.
A smaller simpler circuit board costs less and is more reliable.

These reasons explain why gate arrays are widely used.

Make any Gate from NAND

Build these circuits and use the logic probe made from the Bipolar Transistor Switch and LED to test each circuit.

For the Falstad Circuit Simulation, CTRL+Click Make any Gate from NAND
In options, check European Resistors and uncheck Conventional Current.

Alternatively view Gate_Array.txt.
Save or copy the text on the web page. Import the saved or copied text into the Falstad simulator.

Here is the new HTML5 Simulator Site.

Convert a Circuit into NAND Gates

The original circuit is on the left. It has three kinds of gate needing three chips.
The NAND Array equivalent uses more gates but only one chip giving the advantages (Above).
Sometimes the converted circuit has two not gates one after another. These pairs can be removed and replaced with wire.

Make any Gate from NOR

NOR	NOT	OR
AND	NAND	XOR

For the Falstad Circuit Simulation, CTRL+Click Make any Gate from NOR
In options, check European Resistors and uncheck Conventional Current.

Alternatively view Gate_Array_NOR.txt.
Save or copy the text on the web page. Import the saved or copied text into the Falstad simulator.

Here is the new HTML5 Simulator Site.